EDM has always been about the beats. Not to say that vocalists haven't cut a clear path through the scene of the years, but it's always a DJ/producer genre first. That said, your best bet to make into the mainstream (be it radio, TV, or movies) is to have something for people outside of the scene to latch onto. The easiest way to reel them in is with a strong hook, and for that, you need a powerful vocalist.
We've seen many singers come and go. Some have just collected a check while not adding much to the mix, while others feel like their voices were made for the music they're singing to. A great vocalist doesn't just sing the words on the notepad; they truly make you feel something with the way they use their instrument. Just like you need the right snare to pair up with that killer bassline, adding the proper vocalist can turn a good song into an anthem.
These are the vocalists who fit that description, and damn it, DAD loves them for it.